page_title: 7JP4
section_title: 7JP4 Electrical Characteristics
hierarchical_section_title: 7JP4 / 7JP4 Electrical Characteristics
caption_attribution_description: English: This was drawn by me to use as quick reference to stop searching through data sheets.
context_page_description: The 7JP4 is an early black and white or monochrome cathode ray tube. It was a popular type used in late 1940s low cost and small table model televisions. The 7JP4 has a 7" diameter round screen which was often partially masked. Unlike later electromagnetically deflected TV tubes, the 7JP4 is electrostatically deflected like an oscilloscope tube.
context_section_description: Some General Electrical Characteristics are shown below. Second Anode + Grid 2 (Pin 9) and Plates (Pin 10 & 11 and Pin 7 & 8) have a maximum value limit of 6000 volts dc. Internal arcing can be expected when this voltage is exceeded. Actual values are typically in the 4000 to 5500 volt range, and some sets were operated as low as 2000 volts dc. Grid 1 (Pin 3) can receive either a Negative Bias or a Positive Bias. Pin-2 is the brightness voltage, and pin-3 is the video signal which rides on top of DC, and pin-2 is a DC Level which varies with the Brightness Control. Some sets are backwards and have pin-3 on ground and video on pin-2 along with brightness adjustment.
caption: PIN IDENTIFICATION AND ALIGNMENT
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